guys for your input.
Ken, where would you recomend the LED?, my thoughts, between the slit & collimation lens.
The cal. globe is from;
http://www.iceinspace.com.au/forum/s...t+globe&page=2
positioned just behind the beam-splitter to reflect off the back of the splitter onto the slit.
Tried tonight to capture a spec. of lightning -no success.
PS Al, do you do much with the USB microscope?